Objective: Risk factors for hemorrhage due to gastric and/or duodenal ulcer in patients diagnosed by upper gastrointestinal (GI) endoscopy were investigated in the present study. Methods: Medical records of 350 patients (226 males, 124 females) diagnosed as duodenal or gastric ulcers by GI endoscopy in the gastroenterology clinic were scanned retrospectively. Upper GI hemorrhage was detected in 92 patients by upper endoscopic examination. The medical history of non-steroidal anti-inflammatory drugs (NSAIDs) or acetylsalicylic acid (ASA) usage and the presence of coronary artery disease (CAD) were investigated in all patients with or without hemorrhage. Results were evaluated by Chi-square test and logistic regression analysis. Results: The mean age of the patients was 50.4±15.7 years (range: 25 to 82 years). Hemorrhage due to gastric or duodenal ulcer was identified in 92 patients (26%). Mean age was 64.6±11.4 years in patients with hemorrhage and 45.7±13.9 years in patients without hemorrhage. ASA usage was more common than NSAID in patients with ulcer hemorrhage (NSAID usage n=35 (40%); ASA usage n=51 (60%); p=0.035). Hemorrhage was reported in 20% of the females and in 28% of the males who have ulcer (p=0.055). Risk factors for hemorrhage were CAD (OR: 24.75, 95% CI=1.6-96.7, p=0.001), ASA usage (OR: 9.76, 95% CI=2.1-37.5, p=0.021), NSAID usage (OR: 4.72, 95%CI=1.1-16.5, p=0.032), age (OR: 11.59, 95% CI= 2.7-12.1, p=0.001), and male gender (OR: 2.56, 95% CI= 0.8, 9.6, p=0.052). Conclusion: Advanced age, atherosclerosis, male gender and NSAID administration (particularly aspirin) are the major risk factors of upper GI hemorrhage in patients with gastric and/or duodenal ulcer.